[Effects of light quality on the seed germination of main tree species in a secondary forest ecosystem of Northeast China].

This paper explored the effects of light quality on the seed germination of five dominant tree species (Larix kaempferi, Phellodendron amurense, Acer mono, Fraxinus mandshurica, and Pinus koraiensis) in a secondary forest ecosystem of Northeast China, based on the experiments with the seeds of the five tree species in laboratory and those of the P. koraiensis and L. kaempferi in the field. Four treatments of different light quality were designed in laboratory (taking dark as the control), and three treatments of R/FR (the ratio of red light and far red light intensity) were installed in the field. The laboratory experiment showed that light quality had less effect on the seed germination of L. kaempferi, but the seed germination rates of the other four tree species were significantly different under the treatments of different light quality. P. amurense had the highest seed germination rate under white light, whereas A. mono, F. mandshurica, and P. koraiensis had the highest one under the alternative irradiation with red light and far red light (R-FR-R). In consistence with the results in laboratory, the seed germination rate of P. koraiensis in the field decreased with decreasing R/FR ratio, while that of L. kaempferi was less affected. Under natural condition, the R-FR-R fluctuated with the activity of sun-fleck, and the seed germination patterns of A. mono, F. mandshurica, and P. koraiensis could be the adaptation to the sun-fleck environment in forest stand. The germination of large seeds was significantly affected by light quality.